Obama is actually pretty popular among liberals, moderates, and even conservatives. The last tidbit sounds weird, but it's true. According to
2008 exit polls, Obama won 20% of the conservative vote. Even in
2012, after 4 years of nonstop Republican attacks, he still won 17% of the conservative vote, with 11% of Tea Partiers saying they cast their ballots for Obama.
The only people who can't stand him are Republicans and Republican-leaning Independents. In other words, the far-right in the United States. They're basically nutjobs and racists (e.g. birthers), but because they scream louder than anyone else they attract the most attention.
One of the things you'll learn soon enough if you continue watching US politics is there is no such thing as a "center-left party" in the US. Over the last 40+ years, Democrats have moved to the right while Republicans have moved into a mental hospital. You have one party that is ideally suited for hedgefund managers, banks, credit card companies, defense contractors, and the pharmaceutical lobby; we call these center-right politicians the Democrats. They in turn sit across the table composed of religious lunatics and Civil war reenactors; we call these far-right politicians Republicans.
Understanding this will help you realize
why Republicans make zero sense. Nowadays they are a radical insurgency--ideologically extreme, contemptuous of the inherited policy regime, scornful of compromise, unpersuaded by conventional understanding of factors, evidence, and science; and dismissive of the legitimacy of their political opposition.